IMO the source of the new code is less important than the sheer volume of it. Bun does not need to be entirely rewritten; certainly not over a period of a week, possibly not even over a period of a year. Stability is hard-fought and battle-tested. Everyone has a plan until they get punched in the face; and every repository has passing tests until it runs production code.
I agree, I'm just wondering whether the punches have come already. Honestly, the fact that they haven't is against my expectations, my guess was that we'd see a noisy one here a day after merging.
How many lines of translated code would have been acceptable? What about before AI all the machine translated projects that people used for years without a single complaint? The person who did this was the lead for Bun from the get go no? So it stands to reason that they are one of the highest authorities in Bun itself.